Porous Lane Case Study: Hutt Road, Lower Hutt
Porous Lane installed around established pōhutukawa on Hutt Road.
PROJECT AT A GLANCE
Client: Hutt City Council
Delivery: Fulton Hogan
Scope: Stage 1 complete; programme intended to support 26 established pōhutukawa
The challenge
Hutt Road is one of Lower Hutt’s key urban corridors and is home to a line of established pōhutukawa planted many years ago.
As the pōhutukawa have matured, their naturally spreading root systems have continued to develop beneath the surrounding pavement. Pōhutukawa are large, long-lived native trees that can develop extensive root systems, with roots seeking the water, oxygen and growing space needed to support the tree.
When confined beneath impermeable asphalt and compacted ground, these growing roots can come into direct conflict with the pavement above - contributing to the cracking, lifting and repeated repairs evident along Hutt Road.
Doing better than another asphalt repair
Rather than continuing the cycle of patching the pavement - or potentially compromising established roots to accommodate it - Hutt City Council wanted a better long-term approach.
Council approached Watersmart and identified Porous Lane for a trial along the corridor. The objective was not only to replace the damaged asphalt, but to create a pavement that could better coexist with the established pōhutukawa and their root systems.
A pavement designed around a living root system
Porous Lane provides a permeable surface that allows rainfall and air to pass through the pavement into the underlying layers. This supports a more favourable environment around the root zone while maintaining a durable and accessible pedestrian surface above.
The approach recognises a simple principle: mature trees are living infrastructure. Their root systems continue to grow and change over time, so the surrounding pavement needs to accommodate that living system rather than treating the tree as a fixed object within a hard surface.\
Porous Lane also integrates seamlessly with the surrounding asphalt pavement, maintaining the familiar appearance and continuity of the streetscape. To the everyday user, there is little visual indication that the pavement has been constructed differently — yet beneath the surface, it provides a fundamentally different environment for the established pōhutukawa and their root systems.
Stage 1 preparation for Porous Lane installation by local maintenance contractor Fulton Hogan.
WATER: A permeable surface that enables rainfall to move through the pavement.
AIR: Improved opportunity for gas exchange into the pavement and underlying layers.
COEXISTENCE: A surface treatment designed to better accommodate established roots and pedestrian use.
Stage 1 complete
Stage 1 has now been completed by local maintenance contractor Fulton Hogan, replacing sections of cracked and patched asphalt with a continuous Porous Lane surface integrated around the existing pōhutukawa.
The programme is intended to progress along Hutt Road, ultimately giving 26 established pōhutukawa a better opportunity to continue growing and thriving within the urban environment.
Importantly, the trees remain part of the streetscape. Rather than removing mature vegetation to resolve an infrastructure problem, the project demonstrates how thoughtful pavement design can help existing green infrastructure and public infrastructure work together.
Part of a changing corridor
Hutt Road leads towards the newly opened Te Ara Tupua, a transformative piece of walking and cycling infrastructure for the Wellington region. The Porous Lane project complements this investment by demonstrating how the surrounding urban environment can also evolve through more sustainable, resilient and people-focused design.
For Hutt City Council, the project reflects a commitment to accessible, sustainable and long-lasting infrastructure - integrating innovation while protecting the established natural assets that make the corridor distinctive.
A mature tree and a high-quality pavement should not have to compete for the same space. With the right approach, we can design for both.